rm method is_static_remotekey_enabled for channel backups

electrum/lnchannel.py

@@ -417,10 +417,6 @@ class AbstractChannel(Logger, ABC):
         """
         pass
 
-    @abstractmethod
-    def is_static_remotekey_enabled(self) -> bool:
-        pass
-
     @abstractmethod
     def get_local_pubkey(self) -> bytes:
         """Returns our node ID."""
@@ -550,9 +546,6 @@ class ChannelBackup(AbstractChannel):
     def is_frozen_for_receiving(self) -> bool:
         return False
 
-    def is_static_remotekey_enabled(self) -> bool:
-        return False
-    
     @property
     def sweep_address(self) -> str:
         # Since channel backups do not save the static_remotekey, payment_basepoint in